President Obama has been thinking a lot recently about his post-presidency. According to a detailed dispatch in the New York Times, he has been meeting with notable authors and business leaders over late-night dinners and discussing what he will do next.

High on his post-presidential to-do list should be regime change for Iran. No, Barack Obama should not press his successor to invade Iran and set up an occupation government. But the president should use his time after office to nurture and support Iran's democratic opposition in its struggle against Iran's dictator.

For now, the president should hear from some people who disagree with him. The White House "vision committee" should invite Iranian dissidents who recently signed an open letter opposing the Iran deal. They would have interesting comments over late-night cocktails with the commander-in-chief. Obama's aides could send for Gene Sharp, the leading theorist of nonviolent conflict, and Michael Ledeen, the conservative historian who has spent the last 20 years trying to foment political warfare against the regime.

As an elder statesman, Obama should busy himself with the fate of that regime's political prisoners the way Jimmy Carter has taken up the cause of Palestinian statehood. Obama's legacy in foreign policy depends not on the success of the nuclear deal in the short term, but on the success of Iran's democracy movement in the long term.

Obama can't acknowledge this publicly for the remainder of his presidency. He still needs to make sure Iran's hardliners live up to their end of the bargain, and he can't afford to provoke Ayatollah Ali Khamenei. And even if his nuclear deal were not tying his hands while he's in office, history would be. U.S. government programs to support Iranian civil society have not had much success.

George W. Bush authorized U.S. government grants to support Iran's democratic opposition, but in some cases the receipt of this support endangered Iranians brave enough to accept it. Also many Iranians still remember the role the U.S. played in the 1953 coup that unseated Prime Minister Mohammad Mossadegh. U.S. government programs to support Iranian democracy unfortunately are interpreted as an official pursuit of regime change. That's why Obama can be especially helpful once he is out of office -- by supporting the Iranian opposition as a private citizen, allied with other private citizens to shame Iran's government to treat its people better.

Ultimately it's up to Iranians to rise up against a government that suppresses them. But like any "people power" movement, those activists struggling inside the country need solidarity and support from the outside. Former President Obama would be an ideal person to raise private money and awareness for Iranians who seek the same freedoms we take for granted in the West. Who knows better the dynamics necessary to helping build a coalition for political change? He was, after all, a community organizer.

There are a few doses of self-interest here too. For Obama, a plan to champion Iranian democracy after he leaves office is good politics now, to get his nuclear deal. He could privately assure doubtful Democrats like Senator Chuck Schumer that he would devote his energies during the 10 to 15 years ahead to changing the nature of Iran's regime.

And once he has that deal, it's in Obama's interest to ensure that it succeeds, which can only happen if Iran's current rulers fall. As Obama himself told NPR in April, after 15 years Iran's breakout time to produce enough fissile material for a bomb would decrease from around a year to a matter of a few weeks. If in 2030, Iran is ruled by reactionaries as belligerent as today's reactionaries, Obama's signature foreign policy initiative will have only given the regime more time to perfect the means by which it can blackmail the rest of the world. Obama needs to worry today about who will replace Khamenei and his ilk down the road.

Fortunately there are many Iranians who don't want to live under an Islamic police state. Obama can start with the leaders of Iran's Green movement, like Mir Hossein Mousavi, who took to the streets in 2009 and accused Khamenei of stealing Mousavi's electoral victory. Mousavi, like the current regime has opposed sanctions and supported the nuclear program. But Mousavi and others in the opposition are better long-term partners because they also challenge the unaccountable power of the ayatollah. Remember that the international sanctions that are to be dismantled in exchange for more nuclear transparency were imposed because Iran's leaders went forward with a nuclear program condemned by the rest of the world. That kind of defiance is much harder to pull off when leaders have to face an electorate suffering under the resulting sanctions.

Obama would say he is already working with Iranian reformers, like President Hassan Rouhani. But Mousavi remains under house arrest and state executions have gone through the roof, despite Rouhani's initial promises to free political prisoners.

The truth is, Iran's opposition needs all the help it can get. The hope from the deal's proponents is that increased investment and integration into the world economy will open up enough political space for a democratic opposition to thrive someday. But the odds are against them. Before much money trickles down to Iran's middle class, much more will go to the revolutionary guard commanders who oppress them.

The regime sees the threat coming. On his official website on Monday, Ayatollah Khamenei wrote: "We will permit neither American economic influence, nor political influence, nor cultural influence."

He has good reason to be worried. A decade ago in Washington, I met the grandson of Ayatollah Khomeini, the cleric who led the original Islamic revolution in 1979. Back then the grandson, Hossein Khomeini, was an outspoken opponent of the Iranian regime. He told me that he couldn't imagine a scenario where Iran's rulers gave up power in the face of overwhelming nonviolent resistance, the way Slobodan Milosevic ultimately was forced to give up the Serbian presidency in 2000 after Serbians rose up without violence against him. Khomeini told me that when Iran's people rebelled, the current leaders would pay with their lives.

Someone like Obama, who understands nonviolent conflict more than his predecessors, could help avoid such a bloodbath in Iran. He owes as much to the Iranian people. He owes as much to the American people. And ultimately, Obama owes as much to his own legacy.

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

Eli Lake is a Bloomberg View columnist. He was the senior national security correspondent for the Daily Beast and covered national security and intelligence for the Washington Times, the New York Sun and UPI.